1. Field
The present disclosure relates generally to aircraft rotation during takeoff and landing and, in particular, to a method and apparatus for changing a maximum rotation angle for an aircraft during takeoff and landing.
2. Background
Rotation of an aircraft about a pitch axis through the aircraft during takeoff or landing may cause a tail section of the aircraft to come into contact with a surface from which the aircraft is taking off or a surface on which the aircraft is landing. A tail skid assembly attached to the underside of the tail section of an aircraft may be used to substantially prevent the tail section of the aircraft from coming into contact with a surface from which the aircraft is taking off or a surface on which the aircraft is landing.
In this manner, the surface may come into contact with the tail skid assembly before coming into contact with the underside of the tail section of the aircraft. Further, the tail skid assembly may comprise a shock absorber that absorbs and/or dissipates the energy generated in response to contact between the end of the tail skid assembly and the surface.
The maximum angle at which the aircraft may rotate about the pitch axis before the tail skid assembly comes into contact with the surface may be referred to as a “maximum rotation angle” for the aircraft. The maximum rotation angle desired for an aircraft during takeoff may be different from the maximum rotation angle desired for the aircraft during landing.
The maximum rotation angle desired at takeoff and landing may be determined based on the amount of energy generated when the tail skid assembly comes into contact with the surface, the amount of energy that can be absorbed and/or dissipated by the shock absorber in the tail skid assembly, a length of the aircraft, a distance between an end of the tail skid assembly and the bottom of a tail section of the aircraft, and/or other types of factors. Other factors may include, for example, without limitation, a change in the weight of the aircraft between takeoff and landing, reduced fuel weight due to fuel consumption, landing speed, takeoff speed, takeoff and/or landing requirements specific to a particular airport, landing field length (LFL), and takeoff field length (TOFL).
For example, an aircraft may have a lower weight at the time of landing as compared to the weight of the aircraft at the time of takeoff. This reduction in weight may be the result of, for example, without limitation, fuel consumption during flight, the dropping of cargo during flight, and/or other suitable factors.
With this reduced weight for the aircraft, the energy generated when an end of a tail skid assembly for the aircraft contacts the surface on which the aircraft is landing may be less than the energy generated during takeoff when the aircraft does not have the reduced weight. The lower energy generated during landing may allow the aircraft to have a greater maximum rotation angle during landing as compared to takeoff.
Additionally, an aircraft may have different ground clearance requirements when taking off as compared to landing. As used herein, the “ground clearance” for an aircraft may be the distance between the undermost portion of a tail skid assembly for the aircraft that is configured to come into contact with a surface and an underside of the tail section of the aircraft. The ground clearance needed by an aircraft during landing may be less than the ground clearance needed during takeoff.
Further, a lower ground clearance may allow the speed of the aircraft to be reduced to a desired speed during landing as compared to a greater ground clearance. A lower ground clearance may allow a greater maximum rotation angle for the aircraft as compared to a greater ground clearance.
With some currently available aircraft, the maximum rotation angle for the aircraft may not be adjusted between takeoff and landing. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above as well as possibly other issues.